PHP Resize Script not working on new server/domain

I had the resize.php script working on my previous server/domain and when you go to it HERE you can see the division by zero error. BUT! if you go to the same script on the new domain/server HEREits a blank page with no errors which leads me to believe something is not happening like it should be. I'm a quick learner but a bit of a PHP noob. Any advice with simply resizing a php array of images and displaying them I would appreciate any help.

<?php session_start();header("Pragma: public");header("Cache-Control: max-age = 604800");
header("Expires: ".gmdate("D, d M Y H:i:s", time() + 604800)." GMT");

function thumbnail($image, $width, $height) {

    if($image[0] != "/") { // Decide where to look for the image if a full path is not given
        if(!isset($_SERVER["HTTP_REFERER"])) { // Try to find image if accessed directly from this script in a browser
            $image = $_SERVER["DOCUMENT_ROOT"].implode("/", (explode('/', $_SERVER["PHP_SELF"], -1)))."/".$image;
        } else {
            $image = implode("/", (explode('/', $_SERVER["HTTP_REFERER"], -1)))."/".$image;
        }
    } else {
        $image = $_SERVER["DOCUMENT_ROOT"].$image;
    }
    $image_properties = getimagesize($image);
    $image_width = $image_properties[0];
    $image_height = $image_properties[1];
    $image_ratio = $image_width / $image_height;
    $type = $image_properties["mime"];

    if(!$width && !$height) {
        $width = $image_width;
        $height = $image_height;
    }
    if(!$width) {
        $width = round($height * $image_ratio);
    }
    if(!$height) {
        $height = round($width / $image_ratio);
    }

    if($type == "image/jpeg") {
        header('Content-type: image/jpeg');
        $thumb = imagecreatefromjpeg($image);
    } elseif($type == "image/png") {
        header('Content-type: image/png');
        $thumb = imagecreatefrompng($image);
    } else {
        return false;
    }

    $temp_image = imagecreatetruecolor($width, $height);
    imagecopyresampled($temp_image, $thumb, 0, 0, 0, 0, $width, $height, $image_width, $image_height);
    $thumbnail = imagecreatetruecolor($width, $height);
    imagecopyresampled($thumbnail, $temp_image, 0, 0, 0, 0, $width, $height, $width, $height);

    if($type == "image/jpeg") {
        imagejpeg($thumbnail);
    } else {
        imagepng($thumbnail);
    }

    imagedestroy($temp_image);
    imagedestroy($thumbnail);

}

if(isset($_GET["h"])) { $h = $_GET["h"]; } else { $h = 0; }
if(isset($_GET["w"])) { $w = $_GET["w"]; } else { $w = 0; }

thumbnail($_GET["img"], $w, $h);

?>

I would make sure errors are turned on for debugging, check if the GD library is enabled using phpinfo(), and make sure that the directory where the thumbs are created is writable.